Grinding apparatus for fibrous materials



Y- 1964 A. J. A. ASPLUND ETAL 3,153,333

GRINDING APPARATUS FOR FIBROUS MATERIALS 7 Sheets-Sheet 1 Filed NOV. 7.1961 INVENTORS ARNE JOHAN ARTHUR ASPLUND LARS PENTEN JOHAN GUNNAR INGEJOHANSSON BY 4 Q2 1964 A. J. A. ASPLUND ETAL 3,153,333

GRINDING'APPARATUS FOR FIBROUS MATERIALS Filed Nov. 7, 1961 7Sheets-Sheet 2 1964 A. J. A. ASPLUND ETAL 3,158,333

GRINDING APPARATUS FOR FIBROUS MATERIALS 7 Sheets-Sheet 3 Filed Nov. 7,1961 Nov. 24, 1964 A. J. A- ASPLUND ETAL 3,158,333

GRINDING APPARATUS FOR FIBROUS MATERIALS 7 Sheets-Sheet 4 Filed Nov. 7.1961 Nov. 24, 1964 A. J. A. ASPLUND ETAL 3,153,333

GRINDING APPARATUS FOR FIBROUS MATERIALS '7 Sheets-Sheet 5 Filed Nov. 7,1961 Nov. 24, 1964 A. J. A. ASPLUND ETAL 3,153,333

GRINDING APPARATUS FOR FIBROUS MATERIALS 7 Sheets-Sheet 6 Filed Nov. '7.1961 Fig. 6

Nov. 24, 1964 A, J, A. ASPLUND ETAL 3,158,333

GRINDING APPARATUS FOR FIBROUS MATERIALS Filed Nov. 7, 1961 '7Sheets-Sheet 7 United States Patent 3,158,333 GRINDING APPARATUS FQRFIBROUS MATERIALS Arne Johan Arthur Asplnnd, Bromma, Lars Penten,

Lidingo, and Johan Gunnar Inge Johansson, Nasbypark,

Sweden, assignors to Defibrator Alrtieholag, a corporation of SwedenFiled Nov. 7, 1961, Ser. No. 150,819 Qlaims priority, application SwedenNov. 8, 1960 2 Claims. (Cl. 241-244) This invention relates to grindingapparatus for fibrous materials.

More particularly this invention relates to grinding apparatus fortreatment of fibrous material of organic origin.

Still more particularly this invention relates to grinding apparatus forfibrous materials, said apparatus being of the type comprising a frame,a housing disposed in said frame, two grinding members enclosed in saidhousing one of said grinding members being secured in said housing andthe other on a rotatable shaft, passing through said housing and mountedon either side of said housing on bearings carried by said frame, andcompressing members, preferably in the form of a hydraulic servo-motor,for creating a grinding pressure between said grinding members.

One main object of the invention is to provide a grinding apparatus ofthe kind set forth provided with a device which permits the housing andthe frame to be subjected to different thermal expansion while theymaintain the desired parallel relation between the grinding surfaces ofthe grinding members.

A further object of the invention is to provide a grinding apparatus ofthe type set forth with a device which permits an axial movement of thehousing relatively to the frame while the center position is maintainedpractically unchanged.

Further objects and advantages of the invention will become apparentfrom the following description, considered in connection with theaccompanying drawings which form part of this specification and ofwhich:

FIG. 1 is an elevation of a grinding apparatus or refiner for fibrousorganic material and embodying the invention.

FIGS. 2 and 3 are vertical longitudinal sections on a larger scale ofthe right part and the left part, respectively, of the refiner shown inFIG. 1.

In FIG. 4 is a section taken along the line IV-1V of FIGS. 2 and 3.

FIG. 5 is a view on a larger scale made to the right of a vertical planethrough the shaft axis and partly representing a section following lineVV of FIG. 1; the left part of said FIG. 5 being a view partly insection along line VaVa of FIG. 1.

FIGS. 6 and 7 are sections taken along lines VI-VI and VII-VII,respectively, of FIGS. 1 and 3.

Referring to the drawings, reference numeral 10 denotes the frame of therefiner. The central portion of said frame has a recess intended toreceive a separate grinding housing 12. The housing 12 enclosesstationary and rotatable grinding members generally denoted by 14 and16, respectively. The stationary grinding members 14 are rigidly mountedin the housing 12, while the grinding members 16 are secured to a shaft18 driven via a coupling 20, by a motor 22 (FIG. 1). In known manner,the coupling 20 is of a type permitting'an axial movement of the shaft18 in relation to the motor 22. The shaft 18 passes through and issealed against the grinding housing 12 by means of packing boxes 23, 24at each end of the housing. In the grinding housing a super-atmosphericsteam pressure may be maintained. The shaft 18 is carried by twobearings denoted generally by 25, 28. The two bearings are located inthe frame 18 on either side of the housing 12. The bearings permit dueto differences in temperature during operation.

ICC

Patented Nov. 24., 19654 an axial displacement of the shaft 18 and thegrinding members 16 relatively to the housing and frame.

The grinding housing 12 is divided in a horizontal plane located abovethe shaft 18, its cover 30 being secured to the housing by means of abolting 32. The opening of the housing exposed upon removal of the coveris large enough for rendering it possible to mount the grinding membersthrough the opening. The housing 12 is secured to the frame 10 by aplurality of fastening bolts 34 the number of which in the embodimentillustrated in the drawings is three, and these bolts join the two partson either side of the shaft. The bolts 34 are disposed so as to preventthe tensile forces transmitted through the bolts due to the grindingpressure acting between the grinding members, from creating any bendingmoment in the grinding housing. For this purpose the bolts 34 are fixedin the cylindrical peripheral zone of the grinding housing 12.

The grinding housing 12 has a tubular prolongation 36 in which a sleeve37 is fitted. A gap 46 is formed between said sleeve and the shaft 18 ora wearing liner 38 protecting the shaft, for supply of stock to beground to the grinding members at their radially inner edges. Theprolongation 36 has four openings for selective connection of an inletfor the stock. Of these openings, one upper and one lower are closed bycovers 42, td. In the embodiment shown the stock is received through oneof two side openings 46 to which a connecting pipe 47 is attached.

The grinding housing 12 has a comparatively great axial length and istherefore carried by two supports 48 at the end opposite fastening bolts34-. Said two supports are symmetrically disposed about a longitudinalvertical plane through the axis of shaft 18. At the top, i.e. on thelevel with the axis,-each support 48 is secured to the prolongation 36of the housing 12 by means of bolts 5t} and extends therefrom downwardlyto the lower part of the frame 1% Where it is secured to said frame bymeans of one or several bolts 52. The supports 48, which may be unitedat the base by a cross bar 49, thus have comparatively great verticalextension between their securing points. The supports iii prevent thegrinding housing 12 from depending but at the same time they permit anaxial displacement of the housing caused by the different thermalexpansion of the housing and the frame which occurs when the refiner isoperated. This difference is due to the fact that the housing andthe'frame are constructed of materials having different coefficients ofthermal expansion and, further, In this course the supports act as akind of rocker swinging about the lower securing points. The supportsmay be made of sheet material and have transverse reinforcement plates47 along a part of their length in order to prevent buckling. Thesupports due to the comparatively great length of their top portionsdescribe a circular are on a practically constant level, especially asthe expansion movements are small when compared with the dimensions ofthe frame and the housing. In this way, such movements of the grindinghousing are avoided which could jeopardize the parallellity of thegrinding surfaces of the grinding members 14, 16, which parallellity isof vital importance to the capacity of the grinding apparatus to delivera uniform product of the intended grinding degree.

The fastening bolts 34 are located at the end of the housing 12 facing ahydraulic servo-motor, generally r 3 By conduits 63, 64 pressure fluid,such as oil, may be supplied to one end of the chamber and removed fromits opposite end for bringing about desired movements of the piston.

The piston 58 is rigidly connected to a cover which in turn is securedto the cylindrical inner casing 66 of the bearing 26, which casing isaxially displaceable on ribs as in an outer casing 70 rigidly secured tothe frame 16. Two roller bearings 72, '74 of a combined axial and radialthrust type are mounted in the casing 66, which is rotationallystationary together with the piston, said bearings centering the shaft18 and permitting, at the same time the pressure to be transmitted inboth directions from the servo-motor 54 to the shaft 18 and thus to therotating grinding members 16. The casing 66 is kept under radialpressure by means of a plurality of spring-members 76 acting on a shoe'73 which bears against the casing 66. Said shoe also serves to preventthe casing 66 from rotating. The outer bearing rings 80, 82 of thebearings 72, 74 are inserted in a retainer ring 84. This ring has axialthrough-bores housing spring members 86 which act on the bearing rings80, 82, so that these are always in contact with their rollers 72 and7'4, respectively.

The rotating grinding members 16 comprise a rotor disc 88 rigidlysecured to the shaft 13 and constituting an unbroken element extendingabout the shaft. The

rotor 88 carries a parted segment holder 90 secured onto the rotor bymeans of screws 92 which may be disposed in two groups at various radialdistances about the circumference. The segment holders 90 carry in turngrinding segments 94 which are provided with the grinding surfaces fortreating the grinding stock. The segments 94 are greater in number thanthe parts of the holder 90; in the embodiment shown four segments areconnected by a screw joint 96 with the respective part of the twopartholder. These screw joints are suitably disposed at three differentradial distances.

The stationary grinding members 14 comprise an undivided stator ring 98centered on the sleeve 37 forming part of the housing 12. The statorring 98 carries a holder 1G2, suitably split in two parts, by means ofbolts 104 which are arranged, as are also the bolts 92, in two groups atdifferent radial distances. The segment holder 102 carries segments 106secured thereto by means of screw joints 197 distributed in the same wayas the screw joints 96.

The elements 94 and 1%, which are subjected to wear, are introducedtogether with their holders 90 and 162, respectively, into and removedfrom the housing 12 after the top cover 30 of said housing has beenremoved. The split segment holders 90, 102 are retained in theirpositions in the rotor 38 and the stator ring 98 by means of shoulders91 and 1 13, respectively, provided at the periphery. The securing ofthe split holder 102 to the stator ring 98 is facilitated by the latterbeing rotatably carried on the sleeve or inlet liner 37 and turnable bymeans of a pin which is inserted into one of radial holes 108 formed inthe periphery, according as these holes become accessible from outside.For the same purpose holes 109 are formed in the rotor disc 88. Thescrews 104 may be inserted into their screw holes due to an internalbracket 110 supporting the stator ring 98 while the bolts 112 are not inplace and extending up into the cover 30 having a V-shaped opening 111,as is clearly seen from FIG. 4.

In known manner the grinding segments 94, 106 are formed with channelsor grooves on their interfacing surfaces, said channels or groovesextending radially or peripherally, depending on the grinding degreedesired. The pressure exerted by the fibre stock when passing throughthe gap between the grinding'segments in the direction radiallyoutwards, causes the rotor to deflect so that its effective grindingsurface becomes slightly conical. The conicity is of course proportionalto the magnitude of the grinding pressure.

Bolts 112 are threaded into the segment holders 192 1' and pass withplay through the stator ring 98. The bolts 112 also pass with playthrough sleeve-shaped adjustment screws 114 threaded into the stationaryhousing 12 to abut against the stator ring 98 with their inner endportions. The adjustment screws 114 are locked by nuts 116 in theintended axial abutment position against the stator ring. The bolts 112and adjustment screws 114 are spaced circumferentially in the stationarygrinding members and thus also in the bracket 110. By arrangement of thediameter of the circle along which the adjustment screws 114 arepositioned the grinding pressure load on the stationary grinding membersmay be distributed in such a way that the stator ring obtains bydeformation the same or nearly the same form as is conditional on theconicity of the rotating grinding segments under the action of thegrinding pressure. In this way the gap between the rotating andstationary grinding surfaces may be kept constant radially independentof the magnitude of the grind ing pressure. As an example, it may bestated that this effect was attained in one case when the adjustmentscrews 114 were disposed on a pitch circle having a diameter of 900millimeters, the segments 94 or 104 having an external diameter of 1100millimeters.

In the illustrated embodiment the grinding housing 12 has three openings113 (see especially FIG. 4) for the selective connection of an outletfor the finished fibre stock. The openings not utilized are closed bycovers 117 (FIG. 2).

The servo-motor 5 5 is preferably governed by a control device whichcontrols the pressure generated by the servo-motor in dependence of thevarying supply of grinding stock, so that the width of the gap betweenthe grinding discs is maintained almost constant and the grinding degreethus becomes uniform. A control device of this type, which thus altersthe pressure in the chamber 62 on one or the other side of the pistonflange 60 upon a variation of the grinding stock supply, is described inthe Patent No. 2,971,704, and does not form part of the presentinvention. Should the control device fail for some reason or another,the grinding gap is adjusted instead by means of a device comprising astop nut 118 threaded on the servo-motor piston 55%. This nut isprovided also on its external side with a thread 120 (FIG. 7), adaptedto co-operate with a worm 122 disposed on a shaft 124 and turned by ahand wheel 126. The axial position of the stop nut 118 is adjusted bymeans of the hand wheel 126 in such a way as to cause the grinding gapbetween the grinding members 14, 16 to obtain its intended minimum valuewhen the stop nut is brought to engagement with a thrust bearing 128 inthe stationary servo-motor casing 56. During grinding, the fluidpressure is only conducted to the left end of the chamber 62, as viewedin FIG. 3. The stop nut 118 ensures that disturbing metallic contactdoes not occur between the grinding surfaces. By manual reversing of thepressure fluid flow to the right side of the servo-motor flange 60 thegrinding members are brought apart.

The bearing 28 does not absorb but the radial load from the shaft 18 andfor this purpose it is provided with a spherical roller bearing 13!)mounted in an inner cylindrical bearing casing 132. The latter isaxially slidable in an outer bearing casing 134 and is actuated byspring members 136 via a shoe 138 which also prevents rotation of theinner casing. These elements are essentially of the same type asdescribed in connection with the bearing 26.

Referring to FIG. 6, reference numeral 140 denotes a starting interlockwhich reacts to the axial position of the inner casing 66 and thus tothat of the rotating grinding members. By this interlock the motor 22 isprevented from starting unless the grinding discs are separated.

While one more or less specific embodiment of the invention has beenshown and described, it is to be understood that this is for purpose ofillustration only, and

that the invention is not to be limited thereby, but its scope is to bedetermined by the appended claims.

What we claim is:

1. A grinding apparatus for treating fibrous material comprising, aframe, a housing disposed in said frame, two grinding members disposedin said housing, one of said grinding members being secured in saidhousing and the other mounted on a rotatable shaft passing through saidhousing and mounted on either side of said housing on bearings carriedby said frame, and compressing members adapted to create a grindingpressure between said grinding members, characterized in that saidhousing is secured to said frame at its end facing said compressingmembers for transmitting the tensile load between the housing and frame,the opposite end of the housing being mounted on a support permittingaxial movement of the housing relative to the frame with the centerposition remaining practically unchanged, said support being rigidlysecured to said housing as well as to said frame and having ample radialextension between its points of securement so as to be adapted on anaxial displacement of the housing to perform a swinging movement aboutits point of securement to the frame.

2. A grinding apparatus for treating fibrous material comprising, aframe, a housing disposed in said frame,

two grinding members disposed in said housing, one of said grindingmembers being secured in said housing and the other mounted on arotatable shaft passing through said housing and mounted on either sideof said housing on bearings carried by said frame, compression membersadapted to create a grinding pressure between said grinding members,characterized in that said housing is secured to said frame at its endfacing said compressing members for transmitting the tensile loadbetween the housing and frame, the opposite end of said housing beingmounted on a support permitting axial movement of said housing relativeto said frame with the center position remaining practically unchanged,at least one of the grinding members consisting of a disk-shaped statorring and grinding segments carried by it by means of a split seg mentholder, the parts of the segment holder each having a plurality of saidgrinding segments secured to it, a support ring disposed in the housingand having at its top portion a recess for enabling the grindingsegments,- after introduction into the housing, to be threadably securedto the segment holder.

References Cited in the file of this patent UNITED STATES PATENTS

1. A GRINDING APPARATUS FOR TREATING FIBROUS MATERIAL COMPRISING, AFRAME, A HOUSING DISPOSED IN SAID FRAME, TWO GRINDING MEMBERS DISPOSEDIN SAID HOUSING, ONE OF SAID GRINDING MEMBERS BEING SECURED IN SAIDHOUSING AND THE OTHER MOUNTED ON A ROTATABLE SHAFT PASSING THROUGH SAIDHOUSING AND MOUNTED ON EITHER SIDE OF SAID HOUSING ON BEARINGS CARRIEDBY SAID FRAME, AND COMPRESSING MEMBERS ADAPTED TO CREATE A GRINDINGPRESSURE BETWEEN SAID GRINDING MEMBERS, CHARACTERIZED IN THAT SAIDHOUSING IS SECURED TO SAID FRAME AT ITS END FACING SAID COMPRESSINGMEMBERS FOR TRANSMITTING THE TENSILE LOAD BETWEEN THE HOUSING AND FRAME,THE OPPOSITE END OF THE HOUSING BEING MOUNTED ON A SUPPORT PERMITTINGAXIAL MOVEMENT OF THE HOUSING RELATIVE TO THE FRAME WITH THE CENTERPOSITION REMAINING PRACTICALLY UNCHANGED, SAID SUPPORT BEING RIGIDLYSECURED TO SAID HOUSING AS WELL AS TO SAID FRAME AND HAVING AMPLE RADIALEXTENSION BETWEEN ITS POINTS OF SECUREMENT SO AS TO BE ADAPTED ON ANAXIAL DISPLACEMENT OF THE HOUSING TO PERFORM A SWINGING MOVEMENT ABOUTITS POINT OF SECUREMENT TO THE FRAME.